The present invention, in some embodiments thereof, relates to catheter cannulas (cannulas), catheters, and catheterization methods, and, more particularly, but not exclusively, to a cannula, a catheter, and a (catheterization) method, for administering a fluid or/and substance to, or for draining a fluid or/and substance from, a treatment space of a body vessel, duct, or cavity, for example, a vein or an artery. Exemplary fluids or/and substances are drugs, infusion therapy products, and blood products.
In various interventional medical procedures it is desirable to place a catheter within a patient's blood vessel for purposes of infusion of drugs or fluids, and/or for withdrawing blood. Most commonly, such catheters are first inserted into a blood vessel, and then connected to a supply container for the introduction of fluid by gravity flow or under positive pressure into the vessel.
Vascular access with catheters was introduced more than 100 years ago. It is well known in the medical field that chronic placement of a catheter in a patient's blood vessel often results in catheter failure due to aspiration of the blood vessel wall into the tip of the catheter, clot or thrombus formation at the tip of the catheter, local inflammation, e.g. phlebitis or thrombophlebitis and/or stenosis around the tip of the catheter. A catheter failure resulting from one or more of these mechanisms is evidenced by the inability to aspirate and/or infuse fluid through the catheter, commonly known as catheter occlusion. Typically, catheter occlusions caused by aspiration of the blood vessel wall or clot formation at the catheter tip may be resolved by repositioning the catheter tip or infusing antithrombotic agents.
Some progress has been made in this regard. Following are several exemplary teachings of various designs of catheter apparatuses that address issues of catheter dislodgement, or/and their inability to aspirate, or/and infuse fluid through the catheter.
US Pat. Appl. Pub. No. 2008/0312599 A1 relates to a catheter apparatus that resides in a fixed position within a blood vessel. As shown in FIG. 1, the catheter apparatus 100 has anchoring elements 160 and 161 which are pulled out when the handle 170 is pulled. Possible limitations or disadvantages of this invention are twofold: (1) design of the catheter is such that the anchoring elements apparently contact two points of the vessel wall, and (2) the anchoring mechanism requires a considerable reduction of the diameter of the catheter lumen 200, translating to reduction in possible maximum flow rates of liquids through the catheter.
US Pat. Appl. Pub. No. 2005/0256458 A1 relates to a catheter apparatus with anchoring elements, located on the hub or the catheter itself. As shown in FIG. 2, the anchoring elements 115 are opened and closed with a twisting motion of a hub 110. The anchoring elements 115 outwardly extend from the catheter outer surface and get stuck (like spikes) in adjacent tissue or skin, thereby preventing dislodgement of the catheter from its intended location. The anchoring is non-specific to the vessel lumen, but to essentially all tissue along the catheter body.
U.S. Pat. No. 5,256,146 relates to an implantable vascular catheterization system incorporating an anchoring mechanism including one or more anchoring elements for maintaining the tip of an implanted catheter at a desired position within the blood vessel. As shown in FIG. 3, each anchoring element (14, 34, 40, 42) is a flexible wire which outwardly extends from the catheter tip, and expands to contact and fit the vessel wall 24. The anchoring mechanism is based on increased contact with the vessel wall, involving increasing pressure on the vessel wall for increasing the grip thereupon.
U.S. Pat. No. 4,114,618 relates to a catheter assembly, including an anchoring flap, that is inserted into a blood vessel for directing medicinal fluids intravenously into the vessel. As shown in FIG. 4, the anchoring flap 39 is mountable onto the catheter assembly for anchoring the catheter. Contact between the catheter and the vein wall, via the flap 39, appears to increase rather than be eliminated.
U.S. Pat. No. 5,509,900 relates to a method and apparatus for retaining a catheter tip in a fixed position within a blood flow and preventing it from contacting a blood vessel wall. As shown in FIG. 5, the apparatus includes anchoring (tip retainer) elements 12 at the distal end of the catheter, for anchoring the tip of the catheter within a blood vessel. The disclosed invention aims to reduce damage to the vein wall 25, 26 by eliminating relative movement between the catheter tip and the vein wall. However, this is achieved by applying pressure and possibly damaging the vessel wall using the anchoring elements
WO 2003/080166 relates to a venous port in which one or more extensions are provided which can selectively remove impediments from an aperture of the port.